Emergence and Supervenience

Saturday, November 26, 2011

A reader asked why I didn't mention supervenience in my recent posts on property dualism. He opines that "the notion was invented to make sense of the position you are arguing against." Let's see.

My Problem With Property Dualism Roughly Stated

I take a property dualist to be one who maintains all of the following propositions:

1. There are irreducibly mental properties.2. There are irreducibly physical properties.3. All particulars are physical particulars.4. Some but not all particulars instantiate both irreducibly mental and irreducibly physical properties.

My problem, roughly, is that I don't understand how a physical particular (a brain, a region of a brain, a brain event, or state, or process) can instantiate one or more irreducibly mental properties. Why should there be a problem? Well, if a physical particular is exhaustively understandable in terms of physics (and the sciences based on it) then there is just nothing irreducibly mental about it, in which case it cannot instantiate an irreducibly mental property. I am making the following assumption:

A. If a nonrelational predicate P is true of a particular x, then there must be something in or about x that grounds P's applicability to x.

So if 'feels pain' is true of a physical particular, and 'feels pain' picks out an irreducibly mental property, then there must be something irreducibly mental about that physical particular. Otherwise there would be nothing in or about the particular that could render the predicate true of the particular. But if there is something irreducibly mental about a physical particular, then that particular is not physical in the sense of being exhaustively understandable in terms of physics.

I find (A) to be self-evident. For suppose you were to deny it. Then you would be countenancing the following: there is some particular x that instantiates a property P-ness even though the nature of x excludes P-ness. You would be countenancing, for example, an electron (which is course a negatively charged particle) which yet instantiates the property of being positively charged. If a particular has a an intrinsic (non-relational) property, then that property expresses what the particular is, its nature (in a broad sense of this term).

Now we have to see whether the notion of supervenience can help me with my problem.

Strong Supervenience

The problem for the nonreductive physicalist is that he must avoid both eliminativism and reductionism but without falling into epiphenomenalism, emergentism, or (of course) substance dualism. Epiphenomenalism cannot accommodate the fact that mental phenomena sometimes enter into the etiology of physical events, while emergentism and substance dualism leave physicalism behind. The problem is to somehow secure the reality, the causal efficacy, and the irreducibility of the mental while maintaining the dependence of the mental on the physical. Nice work if you can get it! What the physicalist needs, it seems, is a dualism of properties together with the idea that the mental properties somehow nonreductively depend on the physical ones. But how articulate this dependency relation?

Enter supervenience. The basic idea is that mental properties are not identical with, but merely supervene upon, physical properties in the way in which ethical properties have been thought (by G. E. Moore, R. M. Hare, and others) to supervene upon natural properties. Suppose A and B are both ethically good. It does not follow that there is any one natural, non-disjunctive, property with which goodness can be identified. Perhaps A is good in virtue of being brave and trustworthy, whereas B is good in virtue of being temperate and just. Goodness is in this sense "multiply realizable." A and B are both good despite the fact that their goodness is realized by different natural properties.

Nevertheless, (i) a person cannot be good unless there is some natural property in virtue of whose possession he is good, and (ii) if a person is good in virtue of possessing certain natural properties, then anyone possessing the same natural properties must also be good. Given that A-properties supervene upon B-properties, the "supervenience T-shirt" might read: "No A-property without a B-property" on the front; "same B-properties, same A-properties" on the back. As Jaegwon Kim puts it, "The core idea of supervenience as a relation between two families of properties is that the supervenient properties are in some sense determined by, or dependent upon, the properties on which they supervene." (Jaegwon Kim, "Epiphenomenal and Supervenient Causation," in Supervenience and Mind: Selected Philosophical Essays, Cambridge University Press, 1995, p. 98.)

Kim's preferred way of cashing this out is in terms of strong supervenience. Let A and B be families of properties closed under such Boolean operations as complementation, conjunction and disjunction. A strongly supervenes on B just in case:

(SS) Necessarily, for any property F in A, if any object x has F, then there exists a property G in B such that x has G, and necessarily anything having G has F.

Applying (SS) to physicalism, we may define the determination thesis of strong supervenience physicalism as the view that, necessarily, (i) for any mental property M, if x has M, then there is physical property P such that x has P, and (ii) necessarily, anything having P has M.

But how does this help me with my problem? If x has M and M is an irreducibly mental property, then, by assumption (A) above, x is at least in part mental, and not wholly physical where 'wholly physical' means 'exhaustively understandable in terms of physics and the sciences based on it.' This problem is not solved by telling me that x cannot have a mental property without having a physical property, and that anything having that physical property must have the mental property. For my problem is precisely how x, which is wholly physical, can have an irreducibly mental property in the first place.

One might respond along the following lines. "Look, the whole idea here is that mental properties are functional properties. So when we say that x, a brain event say, has a mental property, all we mean is that it stands in certain causal relations to sensory inputs, behavioral outputs, and intervening brain events. So what makes the brain event mental is simply the relations in which it stands to inputs, outputs and other brain events. Once you grasp this, then you grasp that the brain event can be wholly physical in nature despite its having a mental property. Mental properties are not intrinsic but relational."

Unfortunately, this won't do. Felt sadness has an intrinsically mental nature that cannot be functionally characterized. A subsequent post will spell this out in detail.

Besides, if the property dualist holds that mental properties are really relational, then, strictly speaking, he is not a property dualist. He is not maintaining that there are two sorts of properties, but that mentality consists of relations and that there are no monadic mental properties. Furthermore, his talk of irreducibility must mean only that that type-type identities fail, that for every mental property there is not one unique physical property with which it is identical. Irreducibility boils down to multiple realizability. Mental 'properties' are irreducible in that they are multiply realizable.

Friday, November 25, 2011

It would be very easy to be a property dualist in the philosophy of mind if one were also a substance dualist. What I am having trouble understanding is how a property dualist can be a substance monist. In contemporary discussions, the one category of substances is that of material substances. 'Property dualism,' then, is an abbreviated name for the position in the philosophy of mind according to which mental and physical properties are mutually irreducible -- hence the dualism -- but had by the only kind of substances there are, material substances. Hence the monism. But having employed the traditional jargon, I'll now drop the irridescent word 'substance' which will undoubtedly cause many to stumble and use 'particular' instead. A particular is an unrepeatable entity. It needn't be a continuant. Events and processes count as particulars.

To come directly to my difficulty. How can an irreducibly mental property be instantiated by a physical particular? An irreducibly mental property is one that is not identical with, or reducible to, any physical property. Examples of mental properties: being in pain; thinking about Thanksgiving dinner; having a blue sensation; wanting a cup of coffee. This post assumes that at least some mental properties are irreducibly mental. Various arguments have been given; this is not the place to rehearse them. An irreducibly physical property is one that is not identical with, or reducible to, any mental property. Examples of physical properties: impedance, ductility, motion, solubility, weighing 10 kg. I will assume that all physical properties are irreducibly physical. (It is not that I rule out idealism; it's that the goddess of blogging reminds me that brevity is the soul of blog.)

To further focus the question we need to exclude relational properties. Weaver's Needle has the property of being thought about by me now. So a physical particular has now an irreducibly mental property. But this is unproblematic because the property in question is relational: it does not affect the Needle in its intrinsic nature. But if my brain is what does the thinking in me, and I am thinking about Weaver's Needle, it is not so easy to understand how my brain, a physical thing, can have the irreducibly mental intrinsic property, thinking about Weaver's Needle. (If you think that is not an intrinsic property, substitute wanting a sloop, given that there is no particular sloop in existence that I want.)

So in what follows by 'irreducibly mental properties' I mean 'irreducibly mental intrinsic properties.'

My question is whether the following tetrad is consistent:

1. There are irreducibly mental properties.2. There are irreducibly physical properties.3. All particulars are physical particulars.4. Some but not all particulars instantiate irreducibly mental and irreducibly physical properties.

You might think there is no problem. Color and shape properties are mutually irreducible. Yet some physical particulars instantiate both color and shape properties. A red ball is both red and spherical despite the mutual irreducibility of redness and sphericity. Imagine that the red ball is red all the way through and not red merely on its surface. This will preempt one from saying that the ball is red in virtue of a proper part of it being red.

So why can't mental and physical properties be had by one and the same physical particular? Doesn't the analogy show that the tetrad is consistent? Mental properties are to physical properties as color properties are to shape properties. Just as one and the same physical particular, a ball say, can be both red and spherical, one and the same particular, a brain (or a portion of a brain or an event or process in a brain) can be both located in a region of space and thinking about Boston or feeling nostalgic.

I will now argue that the analogy is hopeless.

A Point of Disanalogy

Colors and shapes are mutually irreducible, but they are also such that color properties cannot be instantiated without shape properties being instantiated, and vice versa. I am talking about colors and shapes in Sellars' "manifest image," colors and shapes as they appear to normal visual perceivers. No color is a shape; but it is also true that there are no colored particulars without shapes, and no shaped particulars without colors. This is a point of phenomenology. One cannot see a colored particular without seeing something that has some shape or other, and vice versa. (And this is so even if the particular is an after-image.) But only some material things are minds. So we have a disanalogy. Wherever a color property is instantiated, a shape property is instantiated, and wherever a shape property is instantiated, a color property is instantiated. But it is not the case that wherever a physical property is instantiated a mental property instantiated. There are plenty of physical particulars that lack mental features even if it is true that everything with mental features also has physical features. Why the asymmetry? This needs to be explained.

Mental Properties as Emergent Properties

Assuming that all particulars are physical particulars -- that there are no unembodied or disembodied or possibly disembodied minds -- why do only some particulars have mental properties? Probably the most plausible thing to say is that only some physical systems are sufficiently complex to 'give rise' to mentality. This implies that mental properties are emergent: they are system features that are not reducible to or explicable in terms of the properties of the parts of the system even when their causal interactions are taken into account.

Bear in mind that not every system feature is emergent. Suppose a wall is made of 1000 piled stones and nothing else, each stone weighing one lb. It follows that the system -- the wall -- weighs 1000 lbs. But the property of weighing 1000 lbs., though a property of the whole and not of any part, is not an emergent property. For it is determined by the properties of the parts. In a more complicated system, the parts causally interact in significant ways. (The stones in the wall interact too, but in insignificant ways.) Think of a wrist watch. The property of showing high noon, though a system property, is not an emergent property because it is determined by the properties and causal interactions of the parts.

An emergent property is one that is irreducible to the properties and causal interactions of the items in its emergence base, but somehow emerges from that emergence base and remains tied to it. The notion of emergence is a curious and possibly incoherent one, combining as it does the notions of irreducibility and dependency. An emergent property is dependent in that (i) it cannot exist uninstantiated, and (ii) it cannot exist unless the emergence base is sufficiently complex, and will continue to exist only as long as the emergence base retains its 'sufficient complexity.' An emergent property is irreducible in that it cannot be accounted for in terms of the properties and interactions of the items in the emergence base. This suggests that emergent properties are real iff they induce causal powers in their possessors above and beyond the causal powers that are explicable in terms of the items in the emergence base.

My point is that if only some physical systems exhibit mentality, namely, those systems that manifest a high degree of (biological) complexity, then the mental properties of these systems must be emergent properties, properties that induce special causal powers in their possessors. But then we must ask what are the possessors of these emergent mental properties. The system as a whole, no doubt. But what does that mean? The mereological sum of the physical items that make up the system in question? But a mereological sum is too frail a reed to support a property. Indeed, some see no real distinction at all between a sum and its members. We need something more substantial to serve as support of mental properties. But I am at a loss to say what that more substantial something is.

The argument so far is as follows. The red ball analogy fails because only some physical particulars instantiate irreducibly mental properties. This is readily explainable if irreducibly mental properties are emergent properties. Emergent properties are system properties, properties of complex (biological) systems. But then the question arises as to what these emergent properties are properties of. They can't be properties of the parts of a system taken distributively any more than the property of weighing 1000 lbs. can be taken to be a property of the stones composing a wall taken distributively. So emergent properties are properties of wholes or collections of some sort. But this seems problematic.

For one thing, there are many mental properties had by one minded organism. I see a javelina; I hear it; I smell it. All in the unity of one consciousness. The mental properties are not just instantiated; they are co-instantiated, instantiated in or by one thing. If Manny sees, Moe hears, and Jack smells, it does not follow that there is one minded organism that does all three. So if mental properties are emergent system properties we need to know which one item it is that instantiates them and unifies them. The brain as a whole? What does that mean? No matter how we construe wholes, whether as mereological sums, mathematical sets ordered or unordered, aggregates, what-have-you, no whole is 'substantiatial' enough to unify the various mental properties that minded organisms exhibit.

It is also unclear how a mere collection could be the subject of experience. The subject of experience is not merely the support and unifier of mental properties; it is also that which is aware (whether intentionally or non-intentionally) in virtue of the instantiation of the mental propertiers. How could the subject of experience be a collection of objects?

So I remain in the dark as to what exactly property dualism could be if it is supposed to be a coherent position. What is it exactly that instantiates mental properties on this view?

Friday, May 15, 2009

The higher quality emerges from the lower level of existence and has its roots therein, but it emerges therefrom, and it does not belong to that lower level, but constitutes its possessor a new order of existent with its special laws of behaviour. The existence of emergent qualities thus described is something to be noted, as some would say, under the compulsion of brute empirical fact, or, as I would prefer to say in less harsh terms, to be accepted with the "natural piety" of the investigator. It admits no explanation.

If, however, the emergent entities admit of no explanation, if their emergence is a brute fact, then claims of emergence are open to the 'poof' objection. It would appear to be rather unbecoming of a hard-assed physicalist to simply announce that such-and-such has emerged when he can offer no explanation of how it has emerged. If interactionist dualists are supposed to be embarrassed by questions as to how mind and body interact, then emergentists are in a similar boat.

4. Anti-Panpsychism: The basic constituents of the physical world do not have mental properties.

Therefore

5. Mental properties are emergent properties, which implies that there are emergent properties.

The cases for (2) are (3) are overwhelming, so I consider them 'off the table.' Peter agrees. Panpsychism ought to be investigated, but Peter finds it highly implausible, so let's assume it to be false for the sake of this discussion. The crucial premise -- the dialectical bone of contention if you will -- between Peter and me is (1). He accepts (1) while I reject it. It is worth noting that there are at least three ways of rejecting (1): by being a substance dualist, or an idealist (see John Foster's work), or a Thomistic hylomorphic dualist. So I would argue from ~(5) to ~(1). But for now we assume that (1) is true.

I coined the phrase 'ego surfari' some years ago. To go on ego surfari is to type one's name into a search engine in order to see what turns up. The results are often surprising. Today I found Does Emergence Help in Defending Religious Belief? by Sami Pihlström, Helsinki. Excerpt:

One of the few recent contributions in which the combination of (emergentist or supervenientist) physicalism and theism is seriously challenged is William Vallicella’s (1998). [Vallicella, W.F. 1998 “Could a Classical Theist Be a Physicalist?”, Faith and Philosophy 15, 160-180.] He rejects eliminativism, type-type identity theory, supervenientism, emergentism, and ”the constitution view” (i.e., the view that persons are materially constituted beings) as five ”theologically useless physicalisms” (163ff.). The argument is largely based on Kim’s criticism of nonreductive physicalism. Regarding emergentism (167- 170), Vallicella points out that even if the human soul were seen as an emergent substance or as having emergent properties, problems would remain, as neither divine nor angelic consciousness can be understood as emerging from matter, upon any Christian construal: ”It is analytic that emergence is emergence from a physical base, and in the case of God and angels classically conceived there is no physical base. Moreover, it is analytic that to emerge is to come into being, and God’s consciousness does not come into being” (169). Vallicella (170) also argues against Stump’s (1995) Aquinian suggestion of combining materialism and dualism (and the possibility of survival), insisting that an emergent property cannot continue to exist after the physical system whose property it is falls apart.

If a reconciliation of science and theism were possible through emergentism, this would constitute an intellectual breakthrough of enormous magnitude. No doubts about the cultural or generally human significance of the notion of emergence would remain. Unfortunately, the research program run by theistically inclined naturalists seems to me hopeless; as Vallicella (1998, 176) puts it, physicalism and theism are ”competing Weltanschauungen”. One problem with views seeking to reconcile them, and with the on-going discussion of emergence and theism in Zygon (and elsewhere), is – as in the systematically philosophical emergence literature we find elsewhere – an unargued commitment to strong metaphysical realism. It is presupposed that both scientific and religious language purport to refer to a fundamentally concept- and language-independent world and that, therefore, religion and science must be coherently fitted into one grand theory of the world, if we if we want to retain both. Against this assumption, a more Wittgensteinian-oriented thinker may argue that religion and science are different human practices (or groups of practices) with their characteristic normative structures. Quite different ”moves” are allowed in these different (families of) language-games; for example, the ”soul” allegedly rendered ”scientifically acceptable” in emergentism would hardly have a place in religious language-use.

Friday, May 08, 2009

This is a paper I read at the Twentieth World Congress of Philosophy, Boston, Massachusetts, August 10-15, 1998.It explains the notions of strong and global supervenience, notions which will serve as foils in getting a handle on the concept of emergence.

ABSTRACT: Could a classical theist be a physicalist? Although a negative answer to this question may seem obvious, it turns out that a case can be made for the consistency of a variant of classical theism and global supervenience physicalism. Although intriguing, the case ultimately fails due to the weakness of global supervenience as an account of the dependence of mental on physical properties.

Physicalism is popular these days, and to a lesser extent so is classical theism. It should therefore come as no surprise that a number of theists are bent on combining theism with physicalism. But could a classical theist be a physicalist? Is this a coherent doctrinal combination? The classical theist affirms the metaphysically necessary existence of a concrete, purely spiritual being upon which every other concrete being is ontologically dependent. The physicalist, however, is committed to the proposition that everything, or at least everything concrete, is either physical or determined by the physical. To be a bit more precise, physicalism is usefully viewed as the conjunction of an 'inventory thesis' which specifies physicalistically admissible individuals and a 'determination thesis' which specifies physicalistically admissible properties.(1) What the inventory thesis says, at a first approximation, is that every concretum is either a physical item or composed of physical items. As for the determination thesis, what it says is that physical property-instantiations determine all other property-instantiations; equivalently, every nonphysical property-instantiation supervenes on physical property-instantiations. These rough characterizations suggest that theism and physicalism logically exclude one another. If God as classically conceived exists, then the inventory thesis is violated: not every concrete entity is either physical or composed of physical items. And if God exists, it would also appear that the determination thesis is flouted: God's instantiation of his omni-attributes does not supervene on His instantiation of any physical properties: He has none. So at first glance it seems almost crashingly obvious that the classical theist cannot be a physicalist.

But this talk cannot end just yet. For when we get down to the details of formulating precise versions of both the inventory and determination theses, it turns out that there is a way to attempt the reconciliation of theism and physicalism. It is the viability of this way that I aim to explore. But first some background.